1. Field of the Invention
The present invention relates to a construction of an electronic circuit portion of various types of electronic apparatuses such as personal computers.
2. Description of the Related Art
FIG. 7 is a perspective view illustrating the appearance of a notebook personal computer 100 shown as an example of a conventional electronic apparatus. The personal computer 100 comprises a main body portion 110 and a lid portion 120 which is openable/closable in such a manner as be to be folded over the main body portion 110. The main body portion 110 has housed therein an electronic circuit portion 130 (see FIG. 9), and a keyboard 13 is disposed on the top surface of the portion 110. A display section 12 formed of a liquid-crystal display (LCD) device is disposed in the lid portion 120. The display section 12 and the keyboard 13 are connected to the electronic circuit portion 130 through a predetermined means. FIG. 8 is a block diagram illustrating such a basic construction of the conventional notebook personal computer, in which the functions of the computer are considered. In the conventional personal computer, the electronic circuit portion 130 is generally mounted on a single-board computer 15 and housed in the main body portion 110, as shown in FIG. 9.
Referring to FIG. 8, reference numeral 1 denotes a microprocessor section; reference numeral 2 denotes a cashe memory section; reference numeral 3 denotes a numerical computational operation coprocessor section, the above components performing data processing and data control. Reference numeral 4 denotes a main memory section; and reference numeral 5 denotes a basic input/output system (BIOS) section. Reference numeral 6 denotes a diskette controller section (for floppy disks); and reference numeral 7 denotes a diskette drive section (for floppy disk drives), the above components being used for driving a floppy disk (not shown). Reference numeral 8 denotes a hard disk drive section. Reference numeral 9 denotes a graphic subsystem section; and reference numeral 12 denotes a display section, these components forming a display function section. Reference numeral 11 denotes a disk emulator section which is used to provide compatibility between the microprocessor 1 and other devices such as disks. Usually, this type of system has two types of buses: a main bus 40 and an input/output bus 41 which is a low speed bus. The components designated by reference numerals 1 to 9, and 11 and 12 are connected to the main bus 40. Reference numeral 10 denotes a bus interface section for interfacing between the main bus 40 and the I/O bus 41; reference numeral 13 denotes a keyboard; reference numeral 13a denotes a keyboard controller section; reference numeral 14 denotes an expansion memory card for expanding memory when the capacity of the main memory section 4 is insufficient. The components designated by reference numerals 13, 13a and 14 are connected to the I/O bus 41.
All the above-described components except the display section 12 and the keyboard 13 are mounted on the single-board computer 15 as shown in FIG. 9. The diskette drive section (for floppy disk drives) 7 and the hard disk drive section 8 are connected onto the single-board computer 15 through a flat cable (not shown) or the like. The other components are mounted on the single-board computer 15, each component having a different IC package configuration. Discrete components (not shown) such as resistors or capacitors are also mounted on the single-board computer 15.
The configuration of an IC package for each functional blocks has various forms, for example, DIP (Dual In Line Package), PGA (Pin Grid Array), SOP (Small Outline Package), or PLCC (Plastic Leaded Chip Carrier). Generally, these IC packages are all hybrid-mounted on one board. The display section 12 and the keyboard 13 are connected to the single-board computer 15 through a predetermined connection means. In this example, only the expansion memory card 14 is connected to the single-board computer 15 so the card can be mounted/dismounted easily.
However, as described above, since generally most of the electronic circuit portions of a conventional electronic apparatus are mounted on a single-board computer, problems described below arise:
(1) It is necessary to develop an entirely new single-board computer each time the functions of an electronic apparatus are changed, i.e., a model change is made, thus a tremendous amount of development work is required.
(2) It is necessary to develop a new single-board computer even when a need to change only some of the functions arises, and therefore a tremendous amount of development work and costs are required.
(3) When some of the parts become defective, it takes a great amount of time to locate such defective portions. Furthermore, even if a defective portion can be located, there is a risk in that very fine patterns on the board will be destroyed during repair, in a worst case, the entire single-board computer may be inoperable.
(4) When a serious failure occurs when a user uses the electronic apparatus, it is very difficult to repair the apparatus on site, and therefore it takes a very large amount of time to correct the failure.
(5) Since a diskette drive and a hard disk drive are mounted, a large amount of power is consumed, and therefore it is difficult to drive the electronic apparatus using a battery.
(6) Since a diskette drive and a hard disk drive are mounted, it is difficult to achieve an electronic apparatus which is thin and light weight. Even a 1.8-inch hard disk drive apparatus, which is the smallest one available at present, has a thickness of 10 to 20 mm.
(7) The performance of the single-board computer determines the performance of the electronic apparatus, and therefore it is impossible to change to another apparatus having different functions from the former apparatus.
(8) Since a magnetic storage medium such as a diskette drive or a hard disk drive is used, the electronic apparatus is vulnerable to vibrations and shocks. Also, the electronic apparatus must be handled carefully during carrying and transport thereof, which is troublesome.
(9) Since a diskette drive a nd a hard disk drive are used, access speed is very slow, and thus the electronic apparatus lacks operability.